PSI - Issue 5

Aalil Issam et al. / Procedia Structural Integrity 5 (2017) 1123–1128 Aalil Issam/ Structural Integrity Procedia 00 (2017) 000 – 000

1127

5

pozzolanic products (Vejmelková et al. 2012; Nežerka et al. 2014) . It also decreases L* and increases a* and b* due to the color of the brick.

Table 3. Densities, porosity and hydric properties of mortars. M 1 M 2 M 3 M 4

M 5 1.54 2.63 41.6

M 6 1.42 2.65 46.4

M 7 1.47 2.59 43.4

M 8 1.33 2.58 48.3

M 9 1.23 2.58 52.3

ρ b (g/cm 3 ) ρ m (g/cm 3 )

1.90 2.78 31.6 3.08 0.38

1.76 2.72 35.2 9.79 0.79

1.50 2.70 44.4

1.68 2.68 37.2 7.15 0.69

P (%)

A (kg/m 2 h 0,5 )

11.95

15.09

13.85

11.28

20.71

17.00

Scap

0.88

0.88

0.90

0.82

0.91

0.88

The use of brick dust as aggregate decreases the bulk density ρb and increases the porosity P without overly affecting the matrix density ρ b . This is mainly due to the similarity between the matrix densities of sand and brick dust (about 2.88 g/cm 3 ) and to the increase in water demand. Concerning its effects on the mechanical properties, it leads to a rise in compressive strength thanks to the pozzolanic reaction; however, brick dust increases the P wave velocity and the dynamic E-modulus unless it is used as the sole aggregate (100 %). The P wave velocity depends on mineralogy and porosity, so replacing the sand by brick dust could increase the P wave velocity thanks to the formation of pozzolanic products but could reduce it by increasing porosity. In addition, the use of brick dust as aggregate decreases the lightness L* and increases the parameters a* and b* because of the darkness of the sand and the redness of the brick. The results also showed that the higher the lime/sand ratio, the greater the capillary absorp t ion and the porosity but the lower the compressive strength, the P wave velocity and the dynamic E-modulus. It showed also the same trend with the lightness L* unlike a* and b*.

Table 4. Mechanical and color properties of mortars. M 1 M 2 M 3

M 4 0.86 1097 1.69 81.71

M 5 1.83 1235 1.96 73.09 11.03 16.37

M 6 3.20 1111 1.46 68.80 13.00 18.74

M 7 0.45 959 1.13

M 8 0.95 1102 1.35 77.36

M 9 1.33 998 1.02

CS (MPa)

1.14 1241 2.43 74.10

3.40 1482 3.23 66.11 14.40 20.85

3.69 1223 1.87 65.00 15.15 22.16

V (m/s)

Edyn (GPa)

L* a* b*

84.28

74.00 11.44 16.63

8.32

6.69

5.22

9.33

15.78

14.20

12.02

14.22

3.3. Compatibility of mortars with the calcarenite stone

Mortars used during restoration interventions should be compatible with the masonry stone to be restored and at the same time durable. To that end, many researchers have proposed a set of criteria. Sasse & Snethlage (1997), for example, made compatibility estimations with some tolerance limits, taking the stone properties as the reference level. These estimations comprised the dynamic E-Modulus, the compressive strength, the coefficient of capillary absorption, the hydric and thermal dilations, the water vapor diffusion resistance and the Pull-off strength. According to (Siegesmund & Dürrast, 2014), the most important parameters are strength and elasticity. Joint mortars should have 20 - 60 % of the dynamic E-Modulus and the compressive strength and 50 - 100 % of the coefficient of capillary absorption of the stone. In this study, we focused on these three properties and the color difference ∆ E (1). Table 5 summarizes the comparison of some properties of the formulated mortars and the calcarenite stone. As we can see, mortar M2 shows better mechanical and hydric compatibility with calcarenite stone than the others but it is not compatible in terms of color as the color difference ∆E is high.